Portable Network Graphics (PNG) Specification, version 1.2

This is version 1.2 of the specification for the Portable Network Graphics
image format.
This version was partially superseded by the
joint W3C and ISO/IEC version
on 10 November 2003. However, the International Standard
currently is available only in single-page HTML format, and it omits the
very useful Gamma and
Color tutorials present in this
version. On the other hand, it does include several completely new color
figures that may prove useful to some. (Technical differences between the
two versions are virtually nonexistent and consist solely of minor
clarifications.)